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dos33fsprogs
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rotozoom: update docs

This commit is contained in:
Vince Weaver 2021-01-07 15:54:08 -05:00
parent cba3b2865c
commit a286080e1b
1 changed files with 10 additions and 3 deletions
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13
graphics/gr/rotozoom/rotozoom.s
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@ -1,6 +1,13 @@
; ANGLE in our case it's 0..15?
; optimization (ANGLE=0)
; rotozoomer!
; takes a lores-formatted image in $c00 and rotozooms it
; by ANGLE and SCALE_I/SCALE_F and draws it to the
; lo-res page in DRAW_PAGE
; ANGLE in our case is 0..31
; SCALE_I/SCALE_F is 8.8 fixed point scale multiplier
; optimization (cycles measured at ANGLE=0)
; $6BD76=441,718=2.26fps initial code with external plot and scrn
; $62776=403,318=2.48fps inline plot
; $597b6=366,518=2.73fps inline scrn
@ -45,7 +52,7 @@ rotozoom:
sta NUM1L ; 3
; ca = cos(theta)*scale;
; ca=fixed_sin[(theta+4)&0xf]
; (we use equiv ca=fixed_sin[(theta+8)&0xf] )
lda ANGLE ; 3
clc ; 2